Ecsenius australianus Springer 1988

Dorsal fin XIL13-15 (typically 14), deeply notched between spinous and segmented-ray portions. Anal fin II,15-17 (usually 16). Pectoral fin 13 or 14 (rarely 14). Caudal fin 13. Vertebrae 10 + 21-23 (usually 22). Dentary incisor teeth 44-51 which includes anterior canine teeth very similar in appearance with incisors; posterior canines usually one on each side. Lateral line without vertical pairs of pores, terminating posteriorly at point between verticals fromdorsal-fin spines 10 and 12. With cirrus on posterior rim of anterior nostril; absent on anterior rim.

Oviparous, distinct pairing (Ref. 205).

Dorsal spines (total): 12; Dorsal soft rays (total): 13 - 15; Analspines: 2; Analsoft rays: 15 - 17

Oviparous. Eggs are demersal and adhesive (Ref. 205), and are attached to the substrate via a filamentous, adhesive pad or pedestal (Ref. 94114). Larvae are planktonic, often found in shallow, coastal waters (Ref. 94114).

Ecenius australianus

Ecsenius (Ecsenius) opsifrontalis.—Springer, 1972:4 [Great Barrier Reef].

DESCRIPTION.—Dorsal fin XII, 13–15 (usually 14), deeply notched between spinous and segmented-ray portions. Anal fin II, 15–17 (usually 16). Pectoral fin 13 or 14 (rarely 14). Caudal fin 13. Vertebrae 10 + 21–23 (usually 22). Dentary incisor teeth 44–51 (includes anterior canine teeth, which differ little, if at all, in appearance from incisors); posterior canines usually one on each side. Lateral line without vertical pairs of pores, terminating posteriorly at point between verticals from dorsal-fin spines 10 and 12. Cirrus present on posterior rim of anterior nostril; none on anterior rim.

Preserved Color: Darkly pigmented specimens (Figure 43b) have dark stripe extending posteriorly from postorbital margin to dorsal opercular region; stripe not clearly continuous with broad, dusky stripe on body, which appears to originate posterior to opercle and extend posteriorly onto caudal fin with slight ventral deflection; stripe increasing in intensity at caudal-fin base; another broad, dusky stripe with indistinct origin posterior to pectoral-fin axil extending onto caudal fin with increase in intensity at caudal-fin base; stripes connected by broad, dusky bands, setting off two rows of pale, oblong areas, each row with 7–9 such areas; bands darkest along dorsal body contour. Some specimens exhibit a scarcely noticeable, fine, dark posterior edging of the opercle. Anal fin with broad, dusky submarginal band; other markings on head, body, and fins not distinctive. Faintly pigmented specimens (Figure 43a) exhibit same basic pattern but stripes and bands on body may be almost unrecognizable.

Live Color (Plate 12: figure 2; also Debelius, 1986:92, upper figure, labelled Ecsenius opsifrontalis): Dark postorbital head stripe brownish or blackish, bordered by narrow, bright, pale stripes, which are continuous through eye dorsal and ventral to pupil; another slender, pale stripe extends short distance along dorsal head profile just above eye. Bands and stripes on body vary, according to specimen, from bright reddish orange to dark brownish pink, becoming dark gray posteriorly in all specimens; two rows of bright-white, oblong areas set off by bands and stripes, dorsal row consisting of about 11 areas and ventral row of about 10; body white below ventral stripe.

COMPARISONS.—Ecsenius australianus appears to be most similar (closely related?) to E. fourmanoiri. Within the Opsifrontalis Group, these two species have the highest averages for meristic characters. Some preserved specimens of E. australianus exhibit a faint dark line along the posterior opercular margin, reminiscent of the intensely dark line of E. fourmanoiri, but the line, when present, of E. australianus does not extend to the ventral surface of the head as it does in E. fourmanoiri. The dark opercular margin is not present in the other species of the Group and I hypothesize that it is a synapomorphy for E. australianus and E. fourmanoiri. Also, only in these two species are there adults with broad, darkly dusky bands and stripes such as illustrated in Figures 43b and 48 (some juveniles of E. opsifrontalis duplicate this pattern, Figure 50d). In E. australianus and E. fourmanoiri the intersections of the bands and stripes are never marked with spots or intensifications of pigment. A similar lack of intensified pigment at the intersections is characteristic otherwise only of some populations of E. opsifrontalis.

Ecsenius australianus differs from E. fourmanoiri in having lower average numbers of segmented dorsal-and anal-fin rays and caudal vertebrae (Table 21). It also differs from E. fourmanoiri in lacking a dark stripe on the fleshy pectoral-fin base, in having the dark line along the posterior opercular margin only faintly dusky, the dorsal body stripe indistinctly formed anteriorly in the region above the appressed pectoral fin, and in never having the body markings so intensely dark as may occur in E. fourmanoiri. The color-pattern of E. australianus is reflected in life by the preponderance of orange markings, as opposed to the blackish markings of E. fourmanoiri. Pale, preserved specimens of E. australianus are remarkably similar in color pattern to dark preserved specimens of E. opsifrontalis (particularly specimens from Abaiang, Kiribati, which have the darkest postorbital stripe of any population within the species). The Kiribati specimens (as is true generally for the species), however, have the postorbital stripe continuous with the dorsal body stripe, which is darker than that of E. australianus. Additionally, except for the northern populations, which are well removed from Australia, E. opsifrontalis rarely has more than 15 segmented anal-fin rays, whereas E. australianus rarely has less than 16.

DISTRIBUTION.—Known only from the northern portion of the Great Barrier Reef of Australia.

HOLOTYPE.—AMS I.19481-062, male, 43.4 mm SL, Yonge Reef, collected by Australian Museum party, November 1975.

PARATYPES.—AMS I.19481-018, (5:18–36 mm SL), collected with holotype; AMS I.19454-030 (2:31, 33), I.19472-017 (9:17–39), USNM 278593 (9:24–45), all with same data as holotype; AMS I.18740-018 (6:16–36), Lizard Island, collected by Australian Museum party, November 1975; ANSP 114789 (3:26–39), northern Escape Reef, 24.4–27.4 m depth, J.C. Tyler et al., 24 January 1969; AMS I.22574-026 (1:40), AMS I.22582-035 (4:~15–27), AMS 22619-014 (2:19, 29), AMS I.22621-012 (2:22, 30), AMS I.22637-016 (2:17, 35), ROM 40529 (1:29), all Escape Reef, variously collected during October and November 1981 and October 1982, at depths from 3–22 m; AMS I.20775-046 (1:37), 11°36′S, 144°01′E [near Raine Island], 11 February 1979; AMS I.20756-042 (2:22, 27), Raine Island, 11°43′S, 144°03′E, 11 February 1979; AMS I.20779-088 (7:28–39), Tijou Reef, 13°05′S, 143°57′E, 1979; AMS I.20755-038 (1:39), off Cape Melville, 14°56′S, 144°36′E, 9 February 1979.

The Australian blenny (Ecsenius australianus) is a small marine blennioid fish of the genus Ecsenius. They are small and reddish brown with a white ventral side. Australian blennies inhabit the shallow marine waters of the tropics. They are often found along the Great Barrier Reef and Coral Sea of Australia.